1. Field of the Invention
The present invention relates to a motor control apparatus with a magnetic flux controller, and a machine learning apparatus and a method therefor.
2. Description of the Related Art
Among motor control apparatuses which are used to drive-control a motor is one in which a magnetic flux state of an induction motor is estimated by a magnetic flux estimator based on an input speed command and the magnetic flux is controlled by a magnetic flux controller as disclosed in Japanese Unexamined Patent Publication No. 2013-66342, for example.
While, in a steady state, a magnitude of magnetic flux in an induction motor (hereinafter, referred to simply as “motor”) becomes a value proportional to an excitation current which is a current for forming the magnetic flux, the magnitude of magnetic flux varies with a delay for a time constant depending on a circuit constant of the motor with respect to a variation in the excitation current when varying it such as during an acceleration or a deceleration of the motor. When a current control is performed without the delay being taken into account, there is sometimes a case where a transient phenomenon in which undulation is caused in a speed waveform occurs due to a discontinuous variation in torque when the magnetic flux varies during acceleration or deceleration of the motor.
With an object to solve the above problem, a magnetic flux controller is incorporated in the motor control apparatus, which controls a follow-up excitation current command such that the amount of the magnetic flux is estimated based on the excitation current or excitation current command and the above time constant and the value of the estimation follows a magnetic flux command value as quickly as possible. The time constant for the delay of the magnetic flux variation with respect to the excitation current is a value that depends on the motor circuit constant, and since in an actual motor, there is a case where the time constant does not become as designed, there is a case where it is preferable to adjust the time constant of the magnetic flux estimator so as to conform to that of an actual device. Further, it is possible to improve the follow-up property of the actual magnetic flux with respect to a magnetic flux command by increase the gain of the magnetic flux controller, but when the gain is excessively increased, the current control becomes unstable. Thus, it is desirable to adjust the time constant of the magnetic flux estimator and the gain of the magnetic flux controller to an appropriate value.
Each parameter such as the gain of the magnetic flux controller and the time constant of the magnetic flux estimator has been determined on the basis of the quality thereof by the operator observing by himself/herself the speed waveform of the motor during acceleration and deceleration when a predetermined speed command (e.g., step-like input) is inputted to the motor control apparatus; therefore, an amount of time and effort has heretofore been required in determining optimum parameters.